(a) Field of the Invention
The present invention relates to a device for packaging at least one lithium battery and a method of producing same. More particularly, the present invention is directed to thermosealable packagings for lithium batteries which include a solid polymer electrolyte which is in electrical contact with an anode of lithium or lithium alloy and a cathode containing at least one metallic salt, such as V.sup.6 O.sup.13, TiS.sub.2 or the like.
(b) Description of Prior Art
Lithium or lithium alloy batteries involving the use of a solid polymer electrolyte are known as disclosed for example in the following U.S. Pat. Nos.:
______________________________________ 4,517,265 May 14, 1985 4,652,506 March 24, 1987 4,690,840 September 1, 1987 ______________________________________
JP 1-239759 dated Sep. 25, 1989 by Hitachi-Maxell discloses a sealing material for batteries of the above type which comprises a hot melt bond of dehydro malonic acid which is heat sealed at 200.degree. C.
JP 62-64065 dated Mar. 20, 1987 by Hitachi discloses the use of glass films which are laser beam welded.
JP 61-277151 dated Dec. 8, 1986 by Dai Nippon discloses the use of copolymers of ethylene and acrylic acid containing acetoxyl radicals.
JP 61-248358 dated Nov. 5, 1986, JP 61-185867 dated Aug. 19, 1986, JP 61-74256 dated Apr. 16, 1986 and JP 61-68860 dated Apr. 9, 1986, all by SEIKO disclose the use of copolymers of ethylene and tetrafluoroethylene which are heat sealed at280.degree. C.
JP 1-239759 and JP 61-277151 use partially hydrophilic polar polymers, which do not provide sufficient humidity resistance. The sealing materials of the Hitachi-Maxell, DAI NIPPON and SEIKO references do not perfectly adhere to metals and have only limited resistance to peeling. The sealing material of HITACHI is susceptible to cracking.
All in all, the sealing materials of the prior art run the risk of delamination and leaking and because of a relatively high heat-sealing temperature in all cases, there is a risk of damage to the heat sensitive battery.